package com.ming.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * Scattering : 将数据写入buffer时 可以采用buffer数组 依次写入【分散】
 * Gathering ： 从buffer读取数据时 可以采用buffer数组 依次读
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws IOException {
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);

        //绑定端口到socket 并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        //创建一个buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        //等待客户端连接
        SocketChannel socketChannel = serverSocketChannel.accept();

        int messageLength = 8; //假设从客户端接收八个字节
        //循环的读取
        while (true) {
            int byteRead = 0;
            while (byteRead < messageLength) {
                long l = socketChannel.read(byteBuffers);
                byteRead += l; //累计读取的字节数
                System.out.println("byteRead=" + byteRead);
                //使用流打印  看看当前这个buffer的position 和limit
                Arrays.asList(byteBuffers).stream().map(
                        buffer -> "position=" + buffer.position() + ",limit=" + buffer.limit()).forEach(System.out::println);
            }
            //将多有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.flip());
            //将数据读出显示到客户端
            long byteWrite = 0;
            while (byteWrite < messageLength) {
                long l = socketChannel.write(byteBuffers);
                byteWrite += l;
            }
            //将所有的buffer 进行clear
            Arrays.asList(byteBuffers).forEach(buffer -> {
                buffer.clear();
            });
            System.out.println("byteRead=" + byteRead + ",byteWrite=" + byteWrite + ",messageLength=" + messageLength);
        }
    }
}
